Journal of Peanut Science

Peanut is a typical calcium-preferring crop,and the widespread calcium deficiency in acidic red soils of southern China often results in empty and shriveled pods,thereby reducing yield.The calcium requirements of different seed-type highyield peanut varieties was investigated in this study to explore the customized fertilization strategies.Using Xianghei xiaoguo(V1),a popular edible-purpose small-seed peanut variety in Hunan,and Xianghua522(V2),a large-seed oil-purpose peanut variety,as test materials,a pot experiment was conducted under typical acidic and low-calcium red soil conditions(pH 5.27,soil exchangeable Ca 700 mg/kg),with calcium oxide as the fertilizer source.Three calcium oxide application levels were established as 0 kg/ha(Ca0),750 kg/ha(Ca50),and 1,125 kg/ha(Ca75),representing low(soil background),medium,and high calcium levels,respectively.Plant calcium accumulation,distribution,and utilization were assessed at key growth stages of the peanuts.The leaf calcium content(5.89—15.01 mg/g) and calcium distribution rate(69.89%—78.38 %) of V1 were significantly higher than those of V2(3.36—11.09 mg/g and 60.11 %—73.02%,respectively) throughout the whole growth period,and the calcium accumulation in leaves and the whole plant were also significantly higher than those of V2 after the pegging stage;the apparent utilization efficiency of calcium fertilizer(12.21%) was significantly higher than that of V2(8.85%).In contrast,under calcium application,the calcium distribution rate in shells(3.47%—6.87%),calcium accumulation in kernels(1.44—12.45 mg/plant),and calcium distribution rate in kernels(0.83%—4.84%) of V2 were significantly higher than those of V1(1.62%—5.00 %,0.88—8.05 mg/plant,and 0.43%—2.55%,respectively)throughout the whole growth period.Additionally,V2 exhibited significantly higher calcium pod production efficiency(142.65 g/g) and calcium pod harvest index(17.04%) than V1(86.82 g/g and 11.09 %).In terms of the effects of calcium application,it increased the calcium kernel production efficiency of V2,with the medium calcium treatment significantly increasing it by 20.62%,while V1 showed no significant change.The promoting effects on kernel calcium accumulation and distribution rate at the maturity stage were both greater for V2 than for V1,with kernel calcium accumulation and distribution rate increasing by 159.7 % and 101.3 % for V2,respectively,and 81.7% and 18.9% for V1,respectively.The decrease in the apparent utilization efficiency of calcium fertilizer with increasing calcium application rate was smaller for V2 than for V1.In summary,the two varieties differed in their calcium absorption and utilization strategies,but the difference in whole-plant calcium accumulation of both varieties between the medium and high calcium treatments was consistently small in this experiment,and the medium calcium treatment showed superior calcium utilization efficiency.Therefore,from an economic and efficiency standpoint,a calcium fertilizer application rate of 750 kg/ha is recommended for both varieties in the southern acidic and low-calcium red soil region of China.